7 Deadly Sins and their Combinations.If you arrange the 7 Deadly Sins around a heptagon label them A-G, and connect each Sin to the others, you get 21 secondary sins. For instance Sloth + Pride = Slackers. Link (Via Neatorama)
I rather enjoyed the post, both from a mathematical and theological perspective. But there's no reason to stop at secondary sins. You can count all the possible ways of combining any number of the 7 Deadlies by using the binomial coefficient. The total works out to be 127 ways to put together any number of the seven sins. Or 120 ways, if you don't count each of the seven sins individually.